A low-power, sensor system developed at the University of Michigan 1,000 times smaller than comparable commercial counterparts. It could enable new biomedical implants.

The U-M system’s processor, solar cells, and battery are all contained in its tiny frame, which measures 2.5 by 3.5 by 1 millimeters. It is 1,000 times smaller than comparable commercial counterparts.

The system could enable new biomedical implants as well as home-, building- and bridge-monitoring devices. It could vastly improve the efficiency and cost of current environmental sensor networks designed to detect movement or track air and water quality.

With an industry-standard ARM Cortex-M3 processor, the system contains the lowest-powered commercial-class microcontroller. It uses about 2,000 times less power in sleep mode than its most energy-efficient counterpart on the market today.

The engineers say successful use of an ARM processor— the industry’s most popular 32-bit processor architecture—is an important step toward commercial adoption of this technology.

Greg Chen, a computer science and engineering doctoral student, will present the research Feb. 9 at the International Solid-State Circuits Conference in San Francisco.

“Our system can run nearly perpetually if periodically exposed to reasonable lighting conditions, even indoors,” said David Blaauw, an electrical and computer engineering professor. “Its only limiting factor is battery wear-out, but the battery would last many years.”

“The ARM Cortex-M3 processor has been widely adopted throughout the microcontroller industry for its low-power, energy efficient features such as deep sleep mode and Wake-Up Interrupt Controller, which enables the core to be placed in ultra-low leakage mode, returning to fully active mode almost instantaneously,” said Eric Schorn, vice president, marketing, processor division, ARM. “This implementation of the processor exploits all of those features to the maximum to achieve an ultra-low-power operation.”

The sensor spends most of its time in sleep mode, waking briefly every few minutes to take measurements. Its total average power consumption is less than 1 nanowatt. A nanowatt is one-billionth of a watt.